Purification, Properties and Structure of Ribose 5-Phosphate Ketol Isomerase from Candida Utilis

Abstract

Candida utilis Ribose 5-phosphate ketol isomerase (EC 5. 3. 1. 6) was purified. The enzyme is homogeneous by ultracentrifugal analysis and disc electrophoresis. The isoelectric point of the enzyme is 3.8, Km for R 5-P is 0.108mM and Kis by 5′-AMP and 6-P-G are 0.16mM and 0.61mM, respectively. The thermodynamic parameters, ΔH, ΔG (35°C), ΔS (35°C) and E are 4336 cal/mole, -5629 cal/mole, 32.15 cal/deg•mole and 6360 cal/mole, respectively. The molecular weight of the enzyme is 183, 000 and the enzyme is assumed to consist of three subunits, one with a molecular weight of 75, 000 and two identical subunits each with a molecular weight of 54, 000. © 1976, Japan Society for Bioscience, Biotechnology, and Agrochemistry. All rights reserved.